Recognition using a face image is a very useful technique in security since, unlike a physical key or a password, there is no fear of loss or oblivion. However, the shape of the face is changed depending on the standing position of a user, or an individual difference in body type and the like, and further, the direction of the face is also not constant, and an illumination condition at the time of the recognition is not previously determined. Thus, in order to perform the recognition with high precision, it is indispensable to absorb a change in face pattern caused by these.
Hitherto, as a technique to perform personal identification by using a face image, for example, there is a method disclosed by O. Yamaguchi and K. Fukui (““Smartface”—A Robust Face Recognition System under Varying Facial Pose and Expression,” IEICE Trans. On Information and Systems Vol. E86-D, No. 1, pp. 37-44, 2003. This corresponds to an English translation of Yamaguchi, Fukui, “Face Recognition System “smartface” Robust to Change in Face Direction and Expression” SINGAKURON (D-II), vol. J84-D-II, No. 6, p. 1045-1052, 2001.). By this method, a change in face pattern is suppressed by using moving images, and recognition is performed. In order to perform the recognition with high precision, it is important to collect various personal face patterns from the moving images, however, there is a problem that the pattern collection depends on the direction of the face of the user himself/herself. Besides, since plural images are required for both an input and a dictionary, for example, in a situation in which only one photograph can be used for the recognition, this method can not be applied.
According to a method of JP-2002-157595A (Japanese Patent Application Publication or Kokai 2002-157595), a measurement is previously performed by using a range finder to photograph a three-dimensional shape of a face, and a check is performed while the face shape is moved and rotated so that it has the same face direction as that of a check object. Since the accurate shape is photographed for each individual, the check can be performed while the direction and size of the face are corrected, however, the specific equipment is needed in order to photograph the shape. Besides, with respect to an image already photographed by a normal camera, such as one in, for example, a passport or a license, since the shape can not be obtained, this method can not be applied.
According to a method of V. Blanz and T. Vetter (“A morphable model for the synthesis of 3-D faces,” in Proc. SIGGRAPH, 1999, pp. 187-194.), many face shapes are previously photographed, a model most similar to an input image is created by the linear combination of those, and the recognition can be performed. Although the shape, direction and size of a face and an illumination condition can be estimated from one image, since the three-dimensional shape information of a created face model depends on the previously photographed face shapes, the method can not be necessarily applied to an arbitrary face with high precision. Besides, since many parameters are estimated and the identification is performed, it takes much processing time.
As described above, in order to absorb various changes in human face patterns, although a method is effective in which various face patterns are collected or created by some methods and the identification is performed, in the related art, there have been problems that a lot of images are needed, the special equipment is required, and applicable faces are limited.
The invention has been made in order to solve the problems of the related art, and has an object to provide an image recognition apparatus, an image recognition method and an image recognition program product, which can be applied to an arbitrary face by using a general camera from an arbitrary number of images and by three-dimensional face model creation using three-dimensional shape information.